Structural elements such as ships' decks, loading hatches and the like are traditionally made up of steel beams and arrays of plates. The steel beams are part of a more or less complete frame structure comprising, amongst other things, reinforcements for preventing buckling in said plate arrays. Such constructions are used nowadays for instance as movable vehicle decks in Ro-Ro ships. Since these movable vehicle decks are intended to be lowered down from an elevated, stowed position below an overlying deck, attempts are made to make the deck as light as possible. The desired load capacity for modern Ro-Ro ships is ever increasing, which often means more fixed and movable vehicle decks on board new ships. This increases the requirement for weight savings in the ship. Today's traditionally constructed vehicle decks are however already almost as light as possible when taking account of their structural limitations.